Douglas Harper's Etymology Dictionary
in reference to Mercalli scale, 1900, named for Italian geologist Giuseppe Mercalli (1850-1914), who invented it ("I Terremoti della Liguria e del Piemonte," Naples, 1897). It was a modification of the Rossi-Forel scale (1883).
Usage examples of "mercalli".
This time, a number two on the Mercalli intensity scale which measures earthqiiakes.
He did not remember what it was, just that there was a thing geologists called the modified Mercalli intensity scale.